Detection Of ESR Gene And The Relationship Between Genetype And Prolificacy Performance In Hu Sheep

The estrogen acceptor is that a kind of matches the body activating nucleic acid acceptor in transcribing the factor clan. Study showed that the B allele of estrogen acceptor gene had closely relationship to the high fecundity, the advantage allele with this gene seat carries out a breeding, the inheritance being able to accelerate swinery progresses. It has been reported that ESR gene may be the a major gene or the existence of a close genetic linkage in controling prolificacy perfprmane of small tail han sheep. But reseaches have not shown the population genetic effects of ESR gene in Hu sheep and the correlation between the ESR gene polymorphism and litter size of Hu sheep.We cloned ESR gene, detected the ESR gene polymorphism and analysis the population genetics characteristics of Hu sheep using the application of PCR-SSCP and Real-time Fluorescence PCR. We analysised the correlation between the ESR gene polymorphism and litter size of Hu sheep through quantitative genetics analysis. And established the method of detecting ESR gene in Hu sheep using Real-time Fluorescence PCR.1 In this study single nucleotide polymorphism in exon 1 of the estrogen receptor (ESR) gene was detected by PCR-SSCP in high fecundity sheep breeds Hu sheep. Results indicated that there were three genotypes (AA,BB,AB) in Hu sheep. They are wild homozygous genotype (AA), mutant homozygous genotype (BB), mutant heterozygous genotype (AB).2 Sequencing revealed that there was a C→G mutation in the BB genotype in comparison to the AA genotype. Compared to the partial exon 1 of ESR gene published by GenBank (Accession Number:X98010), the base sequences of the 335bp matches them except the C→G mutation at 363 bp of exon 1 of ESR gene.3 This experiment detected 56 Hu sheep slected randomly. Among them, the AA, AB, BB were 15,32,9, respectively. The statistic results showed that in Hu sheep the frequency of A allele and B allele are 0.554,0.446 respectively and the genotype frequency of AA, AB,BB are 0.262,0.571,0.161, respectively, which indicate the genetic polymorphism of ESR gene. Meanwhile, x2 fitness test showed that the gene frequency and the genotype frequency were in a state of Hardy-weinberg Equilibrium. It indicates that this gene-locus of ESR gene may not be influnced by breeding means, and its heredity was random in the process of the breeding.4 The results of this reaserch declared that the ewes with genetype AB and BB had 0.98 (P<0.01) and 1.47 (P<0.01) lambs more than those with genetype AA in Hu sheep, respectively. Hu sheep with littering records, least squares analysis showed that the AA, AB, BB are 1.20,2.18,2.67, respectively. The Statistic results of the total number born showed that the number born was significantly different (P<0.01) between A A genotype and BB genotype; Between AA genotype and AB genotype and between BB genotype and AB genotype, there are the same result. The B allele of ESR gene has the significantly positive relation to the number born. Meanwhile, compared to the A allele, the degree of dominance of the B allele of ESR gene was 0.333.5 Twanty four samples which are selected respectively and randomly from the three genotypes (AA,BB,AB) were detected by SYBR Green I RTFQ-PCR, and the melting curve and the Tm value were anslyzed. The results showed 7in 8 samples of wild homozygous genotype and all mutant homozygous genotype and the mutant heterozygous genotypes had been detected.The detected rate is 96%.Results showed that the estrogen receptor locus is either major gene that controls the prolificacy in Hu sheep or in close linkage with such a gene. And we established the method of detecting ESR gene in Hu sheep using Real-time Fluorescent PCR. It can provide the theory evidence and technologic way of early state breeding for improving the reproductive performance.